I complained about this about 6 months ago. The problem hasn't gone away.
You (Jeeves) and I had a conversation about what should happen with the ads and the queue. I'm sorry but I can't find the thread or the conversation.
For me nothing has improved. What has changed is that I give up. Once my resources have gone, so have I.
We watch, you (Nordeus) earn, ad providers earn, product producers/manufacturers benefit, we gain resources, we play.
I'm glad and sad to see that others are now suffering the same issue. For me walkrounds are often not working now. Eg. Hit rests, no offers avaliable, exit rests, hit money, blue get free lights up, exit without watching ad, straight back to rests and blue button is lit, watch ad, receive rest pack, (and often the money too! 2 rewards for 1 video?). This walkround is now resulting in a pop up to say there are no rewards, (this is new, within the last week).
It takes longer to get 5 rewards now than it took to get 25 a year ago. Tiring, frustrating, will sapping.
Good luck in finding the cause.